Method for cutting tempered glass

ABSTRACT

A method for cutting a tempered glass including the steps of strengthening a glass substrate to form, from a surface to the inside of the glass substrate, at least one compression stress layer and a tensile stress layer corresponding to the compression stress layer; removing a part of the glass substrate, wherein the compression stress layer is formed in the part of the glass substrate and a predetermined cutting path passes through the part of the glass substrate; and cutting the glass substrate along the predetermined cutting path.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a Divisional application of co-pending applicationSer. No. 13/013,415, filed on Jan. 25, 2011, for which priority isclaimed under 35 U.S.C. §120; this application claims priority ofApplication No. 099102208 filed in Taiwan on Jan. 27, 2010 andApplication No. 099132711 filed in Taiwan on Sep. 28, 2010 under 35U.S.C. §119; and the entire contents of all of which are herebyincorporated by reference.

BACKGROUND OF THE INVENTION

a. Field of the Invention

The invention relates to a method for cutting a tempered glass and apreparatory tempered glass structure for a cutting treatment.

b. Description of the Related Art

Generally, conventional methods for strengthening glass mainly include aheat strengthening treatment or a chemically strengthening treatment.For example, in a typical chemically strengthening treatment such as anion exchange glass strengthening treatment, a glass substrate issubmersed in a bath containing a potassium salt. This causes sodium ionson the glass surface to be replaced by potassium ions from the bathsolution. Under the circumstance, a thin compression stress layer isformed on a skin layer of the glass substrate. As shown in FIG. 1A andFIG. 1B, a tensile stress TS is formed correspondingly inside a temperedglass 100 to compensate the compression stress of a compression stresslayer DOL. Compared FIG. 1A with FIG. 1B, when the compression stresslayer DOL becomes thicker (layer thickness in FIG. 1B is larger thenthat in FIG. 1A), the strength of the tempered glass 100 becomes greaterand the tensile stress TS inside the tempered glass 100 also becomesgreater. Hence, as the tensile stress TS is increased to a considerableextent, the tempered glass 100 being cut is liable to irregularly splitdue to the tensile stress TS. This may result in extremely lowproduction yield.

BRIEF SUMMARY OF THE INVENTION

The invention provides a tempered glass cutting method and a preparatorytempered glass structure to improve the production yield.

According to an embodiment of the invention, a method for cutting atempered glass including the steps of: strengthening a glass substrateto form, from a surface to the inside of the glass substrate, at leastone compression stress layer and a tensile stress layer corresponding tothe compression stress layer; removing a part of the glass substrate,wherein the compression stress layer is formed in the part of the glasssubstrate, and a predetermined cutting path passes through the part ofthe glass substrate; and cutting the glass substrate along thepredetermined cutting path.

According to another embodiment of the invention, a method for cutting atempered glass including the steps of: strengthening a glass substrateby an ion exchange glass strengthening treatment to form, from a surfaceto the inside of the glass substrate, at least one compression stresslayer and a tensile stress layer corresponding to the compression stresslayer; forming at least one trench on the glass substrate at a positionoverlapping the compression stress layer and a predetermined cuttingpath; and cutting the glass substrate along the trench.

According to another embodiment of the invention, a preparatory temperedglass structure for a cutting treatment includes a glass substrate andat least one trench. The glass substrate is given a strengtheningtreatment to form, from a surface to the inside of the glass substrate,at least one compression stress layer and a tensile stress layercorresponding to the compression stress layer. The trench is formed inthe compression stress layer of the glass substrate and overlaps apredetermined cutting path for the cutting treatment.

According to the above embodiments, a part of the compression stresslayer through which a predetermined cutting path passes is removed toreduce corresponding internal tensile stress. Therefore, when one cutsthe tempered glass, a tempered glass block with a demanded size and asmooth facet is obtained to improve the production yield. Further, sincethe remainder part of the compression stress layer outside thepredetermined cutting path is not removed, the effect of strengtheningthe glass substrate is still maintained.

Other objectives, features and advantages of the invention will befurther understood from the further technological features disclosed bythe embodiments of the invention wherein there are shown and describedpreferred embodiments of this invention, simply by way of illustrationof modes best suited to carry out the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A and FIG. 1B show schematic diagrams of a conventional chemicallystrengthened glass.

FIG. 2 to FIG. 4 show schematic diagrams illustrating a tempered glasscutting method according to an embodiment of the invention.

FIG. 5A shows a schematic diagram of a preparatory tempered glassstructure for a cutting treatment, and FIG. 5B shows a schematic diagramof multiple glass blocks cut from the preparatory tempered glassstructure.

DETAILED DESCRIPTION OF THE INVENTION

In the following detailed description of the preferred embodiments,reference is made to the accompanying drawings which form a part hereof,and in which are shown by way of illustration specific embodiments inwhich the invention may be practiced. In this regard, directionalterminology, such as “top,” “bottom,” “front,” “back,” etc., is usedwith reference to the orientation of the Figure(s) being described. Thecomponents of the present invention can be positioned in a number ofdifferent orientations. As such, the directional terminology is used forpurposes of illustration and is in no way limiting. On the other hand,the drawings are only schematic and the sizes of components may beexaggerated for clarity. It is to be understood that other embodimentsmay be utilized and structural changes may be made without departingfrom the scope of the present invention. Also, it is to be understoodthat the phraseology and terminology used herein are for the purpose ofdescription and should not be regarded as limiting. The use of“including,” “comprising,” or “having” and variations thereof herein ismeant to encompass the items listed thereafter and equivalents thereofas well as additional items. Unless limited otherwise, the terms“connected,” “coupled,” and “mounted” and variations thereof herein areused broadly and encompass direct and indirect connections, couplings,and mountings. Similarly, the terms “facing,” “faces” and variationsthereof herein are used broadly and encompass direct and indirectfacing, and “adjacent to” and variations thereof herein are used broadlyand encompass directly and indirectly “adjacent to”. Therefore, thedescription of “A” component facing “B” component herein may contain thesituations that “A” component directly faces “B” component or one ormore additional components are between “A” component and “B” component.Also, the description of “A” component “adjacent to” “B” componentherein may contain the situations that “A” component is directly“adjacent to” “B” component or one or more additional components arebetween “A” component and “B” component. Accordingly, the drawings anddescriptions will be regarded as illustrative in nature and not asrestrictive.

Referring to FIG. 2, a tempered glass 10 according to an embodiment ofthe invention is formed by a glass substrate 12 given a strengtheningtreatment. The glass strengthening treatment, for example, may be an ionexchange glass strengthening treatment. In a typical ion exchange glassstrengthening treatment, the glass substrate 12 is submersed in a bathcontaining a potassium salt. This causes sodium ions on the skin layerof the glass substrate 12 to be replaced by potassium ions from the bathsolution. Under the circumstance, a compression stress layer DOL isformed on the skin layer of the glass substrate 12, and a tensile stressTS is formed inside the glass substrate 12 to compensate the compressionstress of the compression stress layer DOL. In other words, acompression stress layer DOL and a tensile stress layer TOL arecorrespondingly formed in succession from a surface to the inside of theglass substrate 12. When the compression stress layer DOL becomesthicker, the strength and the internal tensile stress TS of the temperedglass 10 become greater. The stress and thickness stratify the followingequation: TS=CS*[Dc/(D−2*Dc)], where TS is the tensile stress, CS is thecompression stress, Dc is the thickness of the compression stress layer,and D is the overall thickness of the tempered glass 10.

When the tempered glass 10 is cut, a proper cutting depth must exceedthe thickness of the compression stress layer DOL; in other words, acrack as a result of cutting may pierce the tensile stress layer TOLinside the glass substrate 12. As the tensile stress TS is increased toa considerable extent, the tip of a fracture irregularly splits due tothe tensile stress TS, as shown in FIG. 2, and thus a demanded size of aglass block cut from the tempered glass 10 fails to be obtained.However, such problem is solved as long as the tensile stress TS insidethe glass substrate 12 is reduced. According to an embodiment shown inFIG. 3 and FIG. 4, since the tensile stress TS is induced to compensatethe compression stress of the compression stress layer DOL, a part ofthe compression stress layer DOL through which a predetermined cuttingpath passes is removed by etching or polishing the glass substrate 12 toreduce corresponding internal tensile stress TS. Therefore, when onecuts the tempered glass 10, a tempered glass block with a demanded sizeand a smooth facet is obtained to improve the production yield. Further,since the remainder part of the compression stress layer DOL outside thepredetermined cutting path is not removed, the effect of strengtheningthe glass substrate 12 is still maintained. Certainly, the method forremoving a part of the glass substrate 12 to relief the tensile stressTS includes, but is not limited to, etching and polishing processes.

Besides, the glass strengthening treatment may be given on any region ofthe glass substrate 12. For example, as shown in FIG. 3, since a bottomsurface 12 a and a top surface 12 b are both given a strengtheningtreatment, a part of the compression stress layer DOL on the bottomsurface 12 a and the top surface 12 b overlapping a predeterminedcutting path is removed. Certainly, the area and depth of a part of thecompression stress layer DOL to be removed are not limited, as long asthe effect of relieving the tensile strength and preventing irregularlycracks is achieved. Besides, the material of the glass substrate 12includes, but is not limited to, sodium calcium silicate glass andaluminosilicate glass. Further, the strengthening treatment is notlimited to the ion exchange glass strengthening treatment exemplifiedabove, and any strengthening treatment capable of forming compressionstress and tensile stress in the glass substrate 12 is suitable for theabove embodiments.

FIG. 5A shows a schematic diagram of a preparatory tempered glassstructure for a cutting treatment, and FIG. 5B shows a schematic diagramof multiple glass blocks cut from the preparatory tempered glassstructure. Referring to FIG. 5A, after a glass substrate 12 is given aglass strengthening treatment such as an ion exchange glassstrengthening treatment, a compression stress layer and a tensile stresslayer are correspondingly formed in succession from a surface to theinside of the glass substrate 12. Further, at least one trench V (suchas multiple trenches shown in FIG. 5A) is formed on a bottom surface 12a and a top surface 12 b of the glass substrate 12 by etching orpolishing processes. The trench V overlaps a predetermined cutting path,and the depth of the trench V is preferably set as slightly larger thanthe thickness of the compression stress layer. As shown in FIG. 5B, whenthe preparatory tempered glass structure is cut along the trench V,multiple tempered glass blocks 14 with a demanded size and a smoothfacet are obtained.

Further, the use of a tempered glass according to the above embodimentsis not limited. For example, the tempered glass may serve as a glasssubstrate or a cover glass of a touch panel. Alternatively, the temperedglass may serve as a glass substrate of a liquid crystal display, anorganic electroluminescence display, an electrowetting display or abi-stable display.

The foregoing description of the preferred embodiments of the inventionhas been presented for purposes of illustration and description. It isnot intended to be exhaustive or to limit the invention to the preciseform or to exemplary embodiments disclosed. Accordingly, the foregoingdescription should be regarded as illustrative rather than restrictive.Obviously, many modifications and variations will be apparent topractitioners skilled in this art. The embodiments are chosen anddescribed in order to best explain the principles of the invention andits best mode practical application, thereby to enable persons skilledin the art to understand the invention for various embodiments and withvarious modifications as are suited to the particular use orimplementation contemplated. It is intended that the scope of theinvention be defined by the claims appended hereto and their equivalentsin which all terms are meant in their broadest reasonable sense unlessotherwise indicated. Therefore, the term “the invention”, “the presentinvention” or the like does not necessarily limit the claim scope to aspecific embodiment, and the reference to particularly preferredexemplary embodiments of the invention does not imply a limitation onthe invention, and no such limitation is to be inferred. The inventionis limited only by the spirit and scope of the appended claims. Theabstract of the disclosure is provided to comply with the rulesrequiring an abstract, which will allow a searcher to quickly ascertainthe subject matter of the technical disclosure of any patent issued fromthis disclosure. It is submitted with the understanding that it will notbe used to interpret or limit the scope or meaning of the claims. Anyadvantages and benefits described may not apply to all embodiments ofthe invention. It should be appreciated that variations may be made inthe embodiments described by persons skilled in the art withoutdeparting from the scope of the present invention as defined by thefollowing claims. Moreover, no element and component in the presentdisclosure is intended to be dedicated to the public regardless ofwhether the element or component is explicitly recited in the followingclaims.

What is claimed is:
 1. A method for cutting a tempered glass, comprisingthe steps of: strengthening a glass substrate to form, from a surface tothe inside of the glass substrate, at least one compression stress layerand a tensile stress layer corresponding to the compression stresslayer; removing a part of the glass substrate, wherein the compressionstress layer is formed in the part of the glass substrate, and apredetermined cutting path passes through the part of the glasssubstrate; and cutting the glass substrate along the predeterminedcutting path.
 2. The method as claimed in claim 1, wherein the glasssubstrate is given an ion exchange glass strengthening treatment.
 3. Themethod as claimed in claim 1, wherein the part of the glass substrate isremoved by etching or polishing.
 4. A method for cutting a temperedglass, comprising the steps of: strengthening a glass substrate by anion exchange glass strengthening treatment to form, from a surface tothe inside of the glass substrate, at least one compression stress layerand a tensile stress layer corresponding to the compression stresslayer; forming at least one trench on the glass substrate withoutsplitting the glass substrate at a position overlapping the compressionstress layer and a predetermined cutting path; and cutting the glasssubstrate along the trench.
 5. A method for cutting a tempered glass,comprising the steps of: strengthening a glass substrate to form, from asurface to the inside of the glass substrate, at least one compressionstress layer and a tensile stress layer corresponding to the compressionstress layer; forming at least one trench on the glass substrate and inthe compression stress layer without splitting the glass substrate toremove a part of the compression stress layer and correspondingly reducea tensile stress along the trench; and forming a scribe line in thetrench to initiate a cutting treatment and define a cutting path for thecutting treatment.
 6. The method as claimed in claim 5, wherein theglass substrate is given an ion exchange glass strengthening treatment.7. The method as claimed in claim 5, wherein the trench is formed byetching or polishing.